scala> implicit def IntToString(arg:Int):String = arg.toString
<console>:11: warning: implicit conversion method IntToString should be enabled
by making the implicit value scala.language.implicitConversions visible.
This can be achieved by adding the import clause 'import scala.language.implicitConversions'
or by setting the compiler option -language:implicitConversions.
See the Scaladoc for value scala.language.implicitConversions for a discussion
why the feature should be explicitly enabled.
implicit def IntToString(arg:Int):String = arg.toString
^
IntToString: (arg: Int)String